The present invention relates to a device for gathering and conveying printed sheets straddling a gathering segment. The device is formed by a conveyor apparatus that is loaded by sheet feeders disposed along a gathering segment, the apparatus having a saddle-shaped support surface for the printed sheets and driven carries.
Devices of this type are used in, for example, gathering and stapling machines, in which a stapling apparatus adjoins the gathering segment.
When the conveyor apparatus of a gathering segment is loaded, the printed sheets transferred by the sheet feeder are often not set down with their rear edge, seen in the conveying direction, at the associated carrier of the conveyor apparatus. Instead, the rear edges of the printed sheets fed by the sheet feeders are set down at a distance in front of sheets already on the conveyor. Or, the printed sheets are set down onto the conveyor apparatus askew due to the dynamic forces occurring upon impact with the carrier or due to a sudden halt in machine operation. Accordingly, the rear edges of the printed sheets fed by the sheet feeders do not align with the rear edges of the printed sheets being conveyed. Previous counteractive measures included slowing the printed sheets fed by the sheet feeders with elements such as brushes or springs that grip the printed sheets by the free-standing surface in a frictional connection and transfer them into a rear end position at the carriers. Often, the sliding behavior between the printed sheets and/or different format sizes will render the elements acting on the printed sheets through friction inadequate for uniformly arranging the printed sheets at the carriers.
In view of the above, it is an object of the present invention to remedy the described drawbacks with an advantageous device.
A device for gathering and conveying a plurality of printed sheets over a conveying path, each sheet having a front edge and a rear edge with respect to a direction of conveyance is provided. The device includes a conveyor device presenting a gathering segment and having a saddle-shaped support surface adaptable to be loaded by sheet feeders disposed along the gathering segment with a plurality of sheets that have legs straddling the saddle-shaped support surface; driven carriers disposed on the conveyor device and spaced apart from one another, wherein the rear edge of at least one of the sheets straddling the saddle-shaped support along the gathering segment is separated from an associated driven carrier; a guide apparatus arranged to raise at least one leg of the at least one sheet away from the saddle-shaped support surface; and a stop apparatus projecting into the conveying path of the at least one raised leg and gripping the front edge of the at least one raised leg, wherein the stop apparatus is removed from the conveying path by the at least one sheet.
The present invention considerably improves reliability of a common reference position of the printed sheets for further processing.
The present invention also includes a method for gathering and conveying printed sheets straddling a gathering segment, on which a plurality of sheet feeders is disposed. The sheet feeders consecutively load printed sheets onto a conveyor apparatus that comprises a saddle-shaped support surface and carriers that are secured to a circulating tension element. At least one leg of a printed sheet supplied to the gathering segment is held at a distance from the support surface, and the sheet is not placed onto the support surface until a stop apparatus acts on the front edge of the printed sheet.
Furthermore, it is possible to allocate the first sheet feeder only one stop apparatus, which grips the printed sheet lying on the support surface by the front edge of the one leg.
Because sheet feeders are exchangeable, it can also be practical to allocate a first sheet feeder an entire transfer apparatus.
In cases where the gathered printed sheets do not have a common defintion position at the end of the gathering segment, a stop apparatus associated with the gathering segment can project into the conveying path of the gathered printed sheets adjoining the last sheet feeder in the conveying direction.